Sensory changes and hypotension have been reported in laboring women after intrathecal sufentanil (IT-Suf). This study examines the effects of IT-Suf in pain-free, progesterone-free, non-volume loaded subjects, i.e., male volunteers. Ten healthy, fasted, male volunteers were randomly assigned to receive an intrathecal injection of either sufentanil or saline in a double-blind fashion. This study is complete.